Sheet feeding apparatus

ABSTRACT

This disclosure relates to apparatus for feeding sheets from a stack wherein the stack is periodically elevated under the influence of sensing means and a feeder head feeds the topmost sheet to feeding devices. The feeder head is mounted above the stack and has associated therewith counterbalance means to permit suction means of the feeder head to lightly engage the top sheet of the stack irrespective of the height thereof.

0 United States Patent [151 3,642,272

Arnold et al. 1 Feb. 15, 1972 [54] SHEET FEEDING APPARATUS [56] References Cited [72] lnventors: Robert Harry Arnold, London; Cyril UNITED STATES PATENTS h l, h f E 2 2:? hm 2,160,491 5/1939 Cemak 793,212 6/1905 McElroy.... [73] Assignee: The Metal Box Company Limited, Lon- 761,104 5/1904 R bi don, England 2,384,046 9/1945 Seybold .271/11 22 F] d: A .8 1970 i l I g pr Primary Examiner-Joseph Wegbreit l AW 26,648 Attorney-Diner, Brown, Ramik & Holt 'm 1 Foreign Application Priority Data [571 ABSTRACT Apr. 9, 1909 Great Britain ..l8,309/69 This discksure relates to PP for feeding Shae from a stack wherein the stack is periodically elevated under the in- [52 us. Cl. ..27l/62 n fluence of Sensing means and a feeder head feeds the topmost 511 Int. Cl ..B65h l/l8 Sheet to feeding devices The feeder head is mounted above 53 n w f Search "271/30, 31 62 28 the stack and has associated therewith counterbalance means to permit suction means of the feeder head to lightly engage the top sheet of the stack irrespective of the height thereof.

9 Claims, 4 Drawing Figures PATENIEBFEB 1 5 1912 3.642.272 sum 2 or 2 l N VE N TO RS Ram #4160 A A/aw CYKIL BoK'f/I Me K C'Raucfl ATTORNEYS SHEET FEEDING APPARATUS This invention relates to sheet feeding apparatus of the kind in which a stack of sheets is supported on a pallet associated with a mechanism operable to raise the stack a predetermined distance in response to a signal initiated by a detector when the top sheet of the stack is below a predetermined level, in which a feeder head, operable to move the top sheet towards feeding elements arranged to move the sheet away from the vicinity of the stack includes suction means arranged to engage the trailing end portion of the top sheet for movement of the sheet towards the feeding elements. Apparatus of this kind will be referred to below as sheet feeding apparatus of the kind described.

Known embodiments of sheet feeding apparatus of the kind described are found to operate satisfactorily if the stack is flat but in practice considerable unevenness is possible, particularly when the sheets have a relatively large area, which may result in the level of the leading end portion, considered in the direction in which the sheet is fed from the stack, differing from that of the trailing end portion of the sheet. Because of this and because the detector in the known embodiments acts on the trailing end portion of the sheet there is no guarantee that the leading edge of the top sheet will be at the correct level for feeding between the feeding elements and it has been usual to endeavor to correct the level of the uppermost sheets of the stack by the manual insertion of wedges between the sheets at appropriate positions along the height of the stack. This entails the constant supervision of an operator to change the positions of the wedges as the stack is raised. It is an object of the invention to provide a sheet feeding apparatus of the kind described which is capable of automatically compensating for back to front unevenness in the stack.

According to the invention there is provided sheet feeding apparatus of the kind described wherein the feeder head is carried by a mounting which extends lengthwise of the direction of movement of a sheet towards the feeding elements and which is supported for movement in a vertical plane towards and away from the top of the stack under control of counterbalance means arranged so to control movement of the feeder head towards the stack that the suction means remains engageable with the top sheet of the stack with a light pressure, irrespective of any vertical displacement between the leading and trailing edges of the top sheet, and wherein the detector comprises a sensing device operable to sense when the leading end portion of the top sheet of the stack is below said predetermined level.

In one embodiment of the invention the end of the mounting nearest the feeding elements is hinged to a stationary support and the counterbalance means comprises a link one end of which is connected to the opposite end of the mounting and the other end of which is connected to a rod connected to a piston slidable in a substantially vertical cylinder, and means arranged to introduce pressurized fluid beneath the piston.

In a preferred form, the sensing device comprises feeler means supported for movement towards and away from the upward path of the leading edges of the sheets of the stack at a position such that the feeler means will cross said path when the top sheet is below said predetermined level, actuating means operable cyclically to move the feeler means towards and away from the stack in timed relation with the operation of the feeder head, and signal-producing means associated with said actuating means and arranged to initiate a signal to the pallet raising mechanism when the feeler means crosses said path. The feeler means may be rockable about a fixed axis by links, movement of which is effected by a rotatable cam. The signal-producing means may include an electric switch for initiating said signal, and switch-operating means associated with said actuating means for operating said switch. The switch-operating means may comprise a pivoted actuator, rocking movement of which into and out of cooperation with the switch is controlled by one of said links.

In order that the invention may be clearly understood one embodiment thereof will now be described by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic side view of a stack of paper or board sheets, illustrating the manner in which the level of the uppermost sheets may be uneven from the back to the front thereof, 1

FIG. 2 (sheet 2) is a side elevational view, partly in section, of apparatus according to the invention,

FIG. 3 is a fragmentary side elevational view of a part of the apparatus of FIG. 1 which is shown in section, and

FIG. 4 is a fragmentary end elevational view of a part of the apparatus of FIG. 2 looking in the direction of Arrow A, FIG. 2

Referring to the drawings, FIG. 1 diagrammatically illustrates the manner in which the level of the uppermost sheets of a stack may be uneven from the back to the front thereof. From this figure it will be observed that the uppermost sheets undulate from the back 1 to the front 2 so that the level of trailing end portion 3 of the top sheet is different from that of the leading end portion 4.

The sheet feeding apparatus, FIG. 2, is of the kind in which a stack 5 of sheets is supported on a pallet 6 associated with a mechanism 7 operable to raise the stack a predetermined distance in response to a signal initiated by a detector when the top sheet of the stack is below a predetermined level. The mechanism 7, being of known kind, is not disclosed in detail but only as a block. A feeder head 8 is, in known manner, operable by a driving shaft 9 to move the top sheet away from the vicinity of the stack. The driving shaft 9 is driven by means, not shown, from a clutch shaft 12. As shown in FIG. 2 the feeding elements are rollers but, if desired, they may be endless bands. The feeder 8 includes suction means 13 which, in known manner, are arranged to engage the trailing end portion 3 of the top sheet and to raise it from the stack for movement by the feeder head towards the feeding elements 10, 11. A blower nozzle I4, also in known manner, is associated with the feeder head and is arranged to blow air beneath the top sheet to assist in the separation thereof from the next sheet to assist in the separation thereof from the next sheet below it during movement of the top sheet towards the feeding elements 10, 11. The suction means 13 usually comprises four suction devices arranged in two pairs, one pair for lifting the top sheet and one pair for moving it forward.

In the known forms of sheet feeding apparatus of the kind described the feeder head 8 is mounted, and adjustable for horizontal position, on a mounting which is fixed to be horizontal relative to the top of the stack, and the driving shaft 9 is a continuous shaft which extends into the feeder head. In the form of the apparatus according to the invention, however, the feeder 8 is carried by a mounting 15 which, while it extends lengthwise of the direction of movement of a sheet towards the feeding elements l0, 11, is supported for movement in a vertical plane towards and away from the top of the stack under control of counterbalance means, indicated generally by the reference 16, arranged so to control movement of the feeder head towards the stack that the suction means 13 remains engageable with the top sheet of the stack, so as to engage the top sheet with a light pressure which is so equated to the weight of the feeder head as to impart thereto an apparent weight of only a few pounds, irrespective of any vertical displacement between the leading and trailing edges of the top sheet. This light weight ensures that the feeder head follows the contour and changing shape and height of the trailing end portion of the sheet irrespective of the height of the leading end portion 4 of the top sheet.

The mounting 15, at the end thereof nearest the feeding elements I0, 11, is hinged at 17, FIG. 3, to a stationary support formed by cheek plates 18 secured to the bearing 19 for the driving shaft 9. The shaft 9 is connected by a universal joint 20 to a second part 9a of the driving shaft which extends into the mounting to control the operation of the feeder head 8. Conveniently, the mounting 15 carries a lead screw 21 by which the position of the head can be adjusted relative to the rear end of the stack. The counterbalance means comprises a link 22 one end of which is connected, as at 23, to the end of the mounting opposite the hinged end thereof, and the opposite end of the link 22 is connected, as at 24, to a rod 25 which, in turn, is connected to a piston 26 slidable in a substantially vertical cylinder 27 which is carried by a bracket 28 fixed to a tie bar 29 of the sheet feeding apparatus. A balance valve 30 introduces pressurized air, from a source not shown, beneath the piston 26 and air is exhausted slowly to atmosphere from a position, not shown, near to the top of the cylinder 27. If desired, the fluid employed may be a liquid instead of air, or alternatively the counterbalance means may consist of a weight, in which event adjustment thereof would be necessary according to the size of the sheets comprising the stack.

The pallet raising mechanism 7 is operable by a signal initiated by an electrical switch 31, for example, a microswitch, controlled by a detector comprising a sensing device operable to sense when the leading end portion 4 of the top sheet of the stack is below a predetermined level. The sensing device comprises feeler means 32, comprising at least one feeler, supported by a rocking bar 33 carried by the frame of the machine with which the sheet feeding apparatus is associated. The feeler means 32 is movable towards and away from the upward path of the leading edges of the sheets of the stack and the position of the feeler means is such that the latter will cross said path, as shown in full lines in FIG. 2, when the top sheet is below said predetermined level. Actuating means, shown as links 34, 35, are operable cyclically to move the feeler means 32 towards and away from the stack in timed relation with the operation of the feeder head 8. To this end the link 35 is pivoted about a fixed axis 36 and carries a cam follower 37 which is retained by a spring 38 in engagement with a cam 39 rotatable with the clutch shaft 12.

Switch-operating means, associated with the actuating means. comprises an actuator 40 pivoted at 41 to the machine frame and carrying a roller 42 which engages a pin 43, FIG. 4, extending laterally from the link 35.

When the apparatus is in operation the clutch shaft 12 controls the cyclic operation of the feeder head and the cam 39 oscillates the feeler means 32, as shown by broken lines in FIG. 2, so that, while the top sheet of the stack is at a level such that it can be fed to the feeder elements I0, 11 by the feeder head, the feeler means merely engages the front end of the stack and the actuator 40 does not actuate the switch 31 to initiate a pallet-raising signal. When, however, the top of the,

stack is below said level the feeler, on being rocked towards the stack, moves across the path of the upward movement of the leading edges of the stack to reach the position shown in full lines in FIG. 2. When this occurs the actuator 40 causes the switch 31 to initiate a pallet-raising signal, which in turn initiates operation of the mechanism 7, so that the latter raises the pallet and stack by a predetermined distance.

As described with reference to the drawings, the feeler means 32 is oscillatable' but, if desired, it may be arranged to be reciprocable.

The rocking bar 33 also carries a plurality of fingers 44, FIG. 2, which are spaced apart along the length of the bar 33 and are arranged to locate the leading edges of the sheets.

To permit the movements of the feeler means and link 34 the feeding roller 11 is cut away as at 45, FIG. 4.

If desired, the pallet-raising signal may be initiated by means other than an electric switch as described above, for example the signal may be initiated hydraulically, pneumatically, or mechanically.

While one embodiment of the invention has been shown for purposes of illustration, it is to be understood that various changes in the details of construction and arrangement of parts may be made without departing from the spirit and scope counterbalance means arranged so to control movement of the feeder head towards the stack that suction means carried by said feeder head remains engageable with the top sheet 01 the stack with a light pressure, irrespective of any vertical displacement between the leading and trailing edges of the top sheet, a detector including sensing means for sensing when the leading end portion of the top sheet of the stack is below a predetermined level, and stack raising mechanism operable under the control of said sensing means.

2. Apparatus according to claim 1, wherein the end of the mounting nearest the feeding elements is hinged to a stationary support and the counterbalance means includes a link one end of which is connected to the opposite end of the mounting and the other end of which is connected to a rod connected to a piston slidable in an upright cylinder, and means for introducing pressurized fluid beneath the piston.

3. Apparatus according to claim 2, wherein the sensing means include feeler means supported for movement towards and away from the upward path of the leading edges of the sheets of the stack at a position such that the feeler means will cross said path when the top sheet is below said predetermined level, actuating means operable cyclically to move the feeler means towards and away from the stack in timed relation with the operation of the feeder head, and signal-producing means associated with said actuating means and arranged to initiate a signal to the stack raising mechanism when the feeler means crosses said path.

4. Apparatus according to claim 3, wherein the feeler means is rockable about a fixed axis by links movement of which is effected by a rotatable cam.

5. Apparatus according to claim 4, wherein the signalproducing means includes an electric switch for initiation said signal, and switch-operating means associated with said actuating means for operating said switch.

6. Apparatus according to claim 5, wherein the switchoperating means comprises a pivoted actuator rocking movement of which into and out of cooperation with the switch is controlled by one of said links.

7. Apparatus according to claim 3, wherein the signalproducing means includes an electric switch for initiating said signal, and switch-operating means associated with said actuating means for operating said switch.

8 Apparatus according to claim 7, wherein the switchoperating means comprises a pivoted actuator rocking movement of which into and out of cooperation with the switch is controlled by one of said links.

9. Apparatus according to claim 1, wherein the sensing means include feeler means supported for movement towards and away from the upward path of the leading edges of the sheets of the stack at a position such that the feeler means will cross said path when the top sheet is below said predetermined level, actuating means operable cyclically to move the feeler means toward and away from the stack in timed relation with the operation of the feeder head, and signal producing means associated with said actuating means and arranged to initiate a signal to the stack raising mechanism when the feeler means crosses said path. 

1. Sheet feeding apparatus of the kind described wherein a feeder head is carried by a mounting which extends lengthwise of the direction of movement of a sheet towards feeding elements and which is supported for movement in a vertical plane towards and away from the top of the stack under control of counterbalance means arranged so to control movement of the feeder head towards the stack that suction means carried by said feeder head remains engageable with the top sheet of the stack with a light pressure, irrespective of any vertical displacement between the leading and trailing edges of the top sheet, a detector including sensing means for sensing when the leading end portion of the top sheet of the stack is below a predetermined level, and stack raising mechanism operable under the control of said sensing means.
 2. Apparatus according to claim 1, wherein the end of the mounting nearest the feeding elements is hinged to a stationary support and the counterbalance means includes a link one end of which is connected to the opposite end of the mounting and the other end of which is connected to a rod connected to a piston slidable in an upright cylinder, and means for introducing pressurized fluid beneath the piston.
 3. Apparatus according to claim 2, wherein the sensing means include feeler means supported for movement towards and away from the upward path of the leading edges of the sheets of the stack at a position such that the feeler means will cross said path when the top sheet is below said predetermined level, actuating means operable cyclically to move the feeler means towards and away from the stack in timed relation with the operation of the feeder head, and signal-producing means associated with said actuating means and arranged to initiate a signal to the stack raising mechanism when the feeler means crosses said path.
 4. Apparatus according to claim 3, wherein the feeler means is rockable about a fixed axis by links movement of which is effected by a rotatable cam.
 5. Apparatus according to claim 4, wherein the signal-producing means includes an electric switch for initiation said signal, and switch-operating means associated with said actuating means for operating said switch.
 6. Apparatus according to claim 5, wherein the switch-operating means comprises a pivoted actuator rocking movement of which into and out of cooperation with the switch is controlled by one of said links.
 7. Apparatus according to claim 3, wherein the signal-producing means includes an electric switch for initiating said signal, and switch-operating means associated with said actuating means for operating said switch. 8 Apparatus according to claim 7, wherein the switch-operating means comprises a pivoted actuator rocking movement of which into and out of cooperation with the switch is controlled by one of said links.
 9. Apparatus according to claim 1, wherein the sensing means include feeler means supported for movement towards and away from the upward path of the leading edges of the sheets of the stack at a position such that the feeler means will cross said path when the top sheet is below said predetermined level, actuating means operable cyclically to move the feeler means toward and away from the stack in timed relation with the operation of the feeder head, and signal producing means associated with said actuating means and arranged to initiate a signal to the stack raising mechanism when the feeler means crosses said path. 